There are many ways for the FaceTime thing: You could use an overlay which shows one screen above and one below and have the characters stand behind the overlay, so that you only see each of their faces.
You can do the same thing with only a background which looks like two backgrounds if you do not yet feel comfortable using overlays. But then you would have to use the phone animations to make it look better because there won’t be a screen.
Same goes for the door: Either use a background with an opened door and one with a closed one and switch scenes. Or use overlays. I am personally a big fan of using overlays because it gives you more to play with and makes most of the things look better.
If you want to close a door as an overlay I would place the opened door overlay and the closed door overlay at the right spots, then set the one you do not want visible to opacity 0% in 0 first. When the door closes you switch the opacity:
INT. BACKGROUND - DAY with OPENDOOR to size X Y in zone n at layer n with CLOSEDDOOR to size X Y in zone n at layer n
&overlay CLOSEDDOOR opacity 0% in 0
###HERE your scene happens ###
&overlay CLOSEDDOOR opacity 100% in 0 AND overlay OPENDOOR opacity 0% in 0
###HERE something happens while the door closes###
(If you are looking for more directing tips you can look on Instagram for #arrowsdirectingtips to find my posting.)